Patent literature 1 discloses, as shown in its FIGS. 2 and 3, the respective edges of upper plate 11 and lower plate 12 are projected forward relative to the center point 20 of the coupling pillar 13, and this projected portions are provided with slopes 23, 24 respectively at the inner surface. This literature describes that such configuration as explained above may serve to avoid an associated problem when a slider for slide fastener is utilized which is configured as illustrated in FIG. 1 of this document, i.e. the coupling head of the fastener element may hit the upper plate due to its tumbling to disrupt the movement of slider, so that easier movement of slider may be facilitated. In the slider for slide fastener of FIG. 1 of this literature, the coupling pillar 3 is projected forward as illustrated and the edges of the upper and lower plates are receded.
In Patent literature 2, as shown in its FIGS. 1 and 2, a slider for slide fastener is disclosed in which each of the upper and lower plates is provided with a slope 20, 20′ that is provided as illustrated in FIGS. 1 and 2. This literature states from its line 45, column 2 that slopes 20, 20′ are steeper at the coupling pillar 15 side, and the steepness decreases toward the flange 13. Further explained is that, by providing such a slider's slope, elements may be rotated to take a suitable orientation, and may smoothly enter into the respective openings so that independent easier coupling may be ensured.